The invention relates to a method of producing inexpensive fireplace logs or the like, and the logs so produced. In the past, there have been various proposals for the construction of synthetic fireplace logs using coal, however, such prior art attempts often have not been commercially feasible since the logs so produced are difficult to make, cannot economically compete with synthetic wood logs, and/or are difficult to bind in satisfactory form. Prior art synthetic logs that do have satisfactory form include charcoal with the coal, and paraffin wax, both charcoal and paraffin wax being relatively expensive, and requiring mixing in a water medium, and application of vacuum pressure for dewatering, and a curing step.
According to the present invention, a coal log is produced having satisfactory form but being much less expensive than prior art logs since no charcoal or paraffin wax are required, and the log is produced by a simple method that does not require any watering, dewatering, and curing steps. According to the method of the present invention, a major portion of ground coal and a minor portion of relatively fine wood fiber material are mixed together substantially at room temperature, a minor portion of slack wax is heated to its melting temperature, and the melted slack wax is mixed with the coal and wood mixture so that a putty-like extrudable mixture is formed, and such mixture is extruded to produce cylindrical logs or the like. The use of slack wax results in a product that is capable of extrusion under ambient conditions, does not require watering, dewatering, and curing, and results in a product that while inexpensive, burns evenly and steadily. Slack wax remains flexible even after extrusion and hardening of the log, which allows construction of a log entirely of ground coal (or ground coal with wood fiber) that has the necessary form for use as a fireplace log or the like. The extrusion step is practiced substantially at 80.degree. to 95.degree. F., and unless the ambient temperature is very cold (i.e., 40.degree. F.) the extrusion can be practiced without addition of extra heat, the mixture of wax, coal, and wood having the desired temperature from the addition of the melted wax alone to result in the extrusion of a log having the desired properties. The manufacture of the log can take place both by batch and continuous processes.
In order to provide a pleasing effect during burning, flame coloring agents may be added to the logs. For instance, the extruded log can be rolled in copper sulphate. Additionally, if necessary, conventional igniters can be added to the mixture to improve the ignition characteristics, conventional igniters including sodium nitrate, potassium nitrate, and potassium chloride.
According to the present invention, a fireplace log is produced consisting essentially of about 55 to 80% by weight of ground coal, approximately 20 to 35% by weight slack wax, and approximately 0 to 10% by weight of wood fiber material. The coal is ground, as opposed to powdered, and the wood fiber material is preferably selected from the group consisting of saw dust and wood shavings, lengthwise grain wood shavings (as opposed to cross-grain wood shavings) being most suitable.
It is the primary object of the present invention to provide a simplified method for the manufacture of synthetic fireplace logs or the like, and to provide an inexpensive fireplace log or the like having suitable characteristics for use as a fireplace log. This and other objects of the invention will become clear from an inspection of the detailed description of the invention, and from the appended claims.